Update:
Evolution seems to show some mails and not others…. am finding that txt emails, or small emails, are viewable offline, but other not…. The search continues….

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Frequently of late, I’m finding I’m not online, so getting through email has not been an option with IMAP, using Evolution on Ubuntu with default settings. So after some reading these are the steps to make it work by downloading mail for offline use:

1. Go to your email account settings dialogue in Evolution: Edit > Preferences > email account > Edit (on the right)
2. Go to “Receiving Options” tab
3. Untick “Automatically synchronise….” at the bottom
4. Then go to the folder you want to be available offline, right click, select “Properties”
5. Tick “Copy folder content….” and “Always check for…..” if you want Evolution to do that
… And that should do it… ;-)

I deleted all IMAP folders on my local machine for my GMail account first, then set it up again doing the above, and it worked like a charm. There is a delay while Evolution gets all your mail to sync to start. You may also want to restrict which GMail folders / labels are available to IMAP so you don’t download *all* your mail…. You may have to deal with this bug, but it’s not a big price to pay for offline mail…